Research Project 3: Oxidized proteins, oxidized lipids and oxidized DNAs are present in the brains of patients with Alzheimer's disease (AD), but are absent or greatly reduced in age matched controls. It has been reported that an anti-oxidant therapy improved the quality of life for AD patients. These findings support the idea that oxidative stress is present in AD and that therapies designed to reduce oxidative stress benefit the patient. Hypothesizing that these oxidized macromolecules found in AD brains resulted from their exposure to oxidizing free radicals, we propose to measure free radical release in humans with and without AD and in animals that model aspects of the disease. Our focus on nitric oxide, together with superoxide and hydrogen peroxide, emerge from an understanding that release of these free radicals give rise to a wide variety of oxidation reactions that ultimately result in the same kinds of oxidized macromolecules seen in AD brains. We propose specific aims to understand the potential causes of this oxidative stress. One goal of these specific aims is to define the ability of cells from patients with different APOE genotypes to produce nitric oxide and/of superoxide as a function of the presence or absence of clinically diagnosed AD. Another goal is to define whether mice transgenic for the human APOE genes respond in the same way as humans. One other goal is to determine whether the response of tissue macrophages from the periphery, accurately models or predicts the response of microglia, the tissue macrophages of the brain. As tissue macrophages are a rich source of free radical production and release, they are implicated in virtually all inflammatory conditions including those that have been described in AD. The last goal is to begin to compare the biochemical pathway beginning with arginine transport into the cell, and ending with its enzymatic conversion by nitric oxide Synthase (NOS) into citrulline and nitric oxide, in cells that display different APOE genotypes. Out Preliminary Results strongly suggest that nitric oxide release in mice varies with APOE genotype providing further justification for this approach.